A touch panel of electrostatic capacitance coupling type has a rectangular-shaped transparent electrode, for example, and when a surface of the touch panel is touched, the transparent electrode is grounded through a human body at a touch position. This brings about a change in an electrostatic capacitance formed between four corners of the transparent electrode and the touch position, and based on this change, the touch position is detected. The touch panel of electrostatic capacitance coupling type has been widely used recently because this touch panel can be mounted on the front surface of a display panel such as a liquid crystal display panel at low cost.
In a liquid crystal display device having a touch panel of electrostatic capacitance coupling type mounted on the front surface of the liquid crystal display panel, electrical noise may reduce accuracy of detecting a touch position. Electrical noise is caused by, for example, an opposite potential that is supplied to a common electrode, which is disposed on an opposite substrate for the liquid crystal display panel, when displaying an image. To solve this problem, in a liquid crystal display device having a touch panel of electrostatic capacitance coupling type mounted thereon, a technique of providing a shielding member that reduces electrical noise between the touch panel and the liquid crystal display panel has been proposed.
Patent Document 1, for example, discloses a liquid crystal display device equipped with an electrostatic capacitance type touch panel disposed on the viewer side of the liquid crystal display device. This liquid crystal display device is provided with a shield layer interposed between the liquid crystal display device and the touch panel. The shield layer is constituted of a transparent conductive film that electrically isolates the touch panel from the liquid crystal display device, and a frame-shaped electrode having a low electrical resistance and formed on the entire circumference of the transparent conductive film in a frame shape. The shield layer blocks electrical noise generated by the liquid crystal display device.
Patent Document 2 discloses a transparent electromagnetic wave shielding film for a touch panel of a liquid crystal display device. The shielding film is disposed on a support member, and has a fine line pattern that is made of conductive metal containing developed silver.